Switching Items in hotbar using numbers causes Items to place the wrong block

Basically, when I use the number keys to switch items in my hotbar, everything looks fine, except that when I place the item I moved around glitches out, and places the block it was before I switched.

For example: Let's say you have stone in slot one, and cobblestone in slot two. Pressing '1' while hovering over slot two will switch the items, but the cobblestone now in slot one will put down stone.